Other versions exist on this site from various publications. This one is from the Radio Electronics Experimenter from 1990. The bargraph circuit uses the UAA170.
This circuit with integrated TTL 7400 has a good teaching purpose, drawing one of two LEDs. The...
The preamplifier using JFET presets a high input impedance and very low distortion. The input...
The figure shows how to generate a sinusoidal signal using 4 flip-flops. The circuit is from a...